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irj 18, 1918. 



U. S. DEPARTMENT OF AGRICULTURE, 

BUREAU OF ENTOMOLOGY CIRCULAR No. 169. 

L. O. HOWARD. Enlomolotiirt »nd Chief ol Burcu. 



SACBROOD, 

A DISEASE OF BEES, 



ny 



G. V. WHITE, M. I).. Ph. D., 






WMHIN^TON : GOVERNMENT PRINTING OFFICE ! lilt 




BUREAU OF ENTOMOLOGY. 

L. O. Howabd, Entomologist and Chief of Bureau. 

C. L. Maklatt, Entomologist and Acting Chief in Absence of Chief. 

R. S. Clifton, Executive Assistant. 
w. F. Tastet, Chief Clerk. 

F. H. Chittenden, in charge of truck crop and -stored product insect investigations. 

A. D. Hopkins, in charge of forest insect investigations. 

W. D. Hunter, in charge of southern field crop insect investigations. 

F. M. Webster, in'charge of cereal and forage insect investigations. 

A. L. Quaintance, in charge of deciduous fruit insect investigations. 

E. F. Phillips, in charge of bee culture. 

D. M. Rogers, in charge of preventing spread of moths, field work. 

Roll*. P. Currie, in charge of editorial work. 

Mabel Colcord, in charge of library. 

Investigations in Bee Culturj . 

E. F. Phillips, in charge. 

G. F. White, J. A. Nelson, experts. 

G. S. Demuth, A. H. McCray, N. E. McIndoo, apicultural assistants. 

D. B. Casteel, collaborator. 
Pearle H. Garrison, preparator. 

ii 



Circular No. 169. ImatA Jtnoarj 16, 1013. 

United Stales Department of Agriculture, 

BUREAU OF ENTOMOLOGY. 

L. O. HOWARD, Entomologist and Chief ol Bureau. 



SACBBOOD, A DISEASE OF BEES. 

r.\ G, I. White, .\i. i >.. rii. n. Expert m Bacteriotooy, 

l\ ll:ol>l < I l(i\. 

The purpose of this preliminary paper i- to disease briefly a dis- 
ease, which has been recognized by the bee keeper- for many years 
as dead brood, that i- different From foul brood. 

Sacbrood, therefore, is no new disease. Samples of it have been 
received from all the States except three, together with samples from 
Canada. This disease really has had no name. In recent years many 
bee keepers have by mistake spoken od it a- " pickled brood." The 

pickled brood a- William R. I low aid describes it. however, i- a \ei\ 

different disease. Before considering sacbrood it might lie well to 
explain briefly what is meant by pickled brood. 

l'l< SUED BBOOD. 

In 1S!)C> William R. Howard, of Texas, wrote a paper in which he 
describes a disease of bees that he call- " pickled brood." He de- 
clared in his paper that the disease was caused by a fungus to winch 
he gave the name Aspergillus pottirtf. In 1898 he wrote a 9econd 
paper in which he says that the fungus may attack not only the 
larvae and pupa? but adult bees a- well. 

M i.i— en in 1906 mentioned a disease of bees which he says is caused 
by a fungus Btated by him to he similar to Aspergillus ftavus ami 
easily isolated from the larva', pupae, and adult bees affected by the 
disease. 

These two men. then. Howard and Maa—en. have each written of 

a disease of bees which they believe to he caused by a fungus. By 

each it is claimed that the fungus can attack adult bees a- well a- the 
larva? and pupa'. Howard named the disease which he mentioned 
"pickled brood," and bfaassen referred to the disease which at- 



1 This .-irrui.ir will be followed by ii bulletin ..f thi< bureau in which this d 
be treated more fully. 



2 SACBROOD, A DISEASE OF BEES. 

tracted his attention as an " aspergillusmycosis in bees." The dis- 
eases, as described by Howard and Maassen. then, would be called 
fungous diseases. 

II' there are any such fungous diseases of bees in the United States 
they have not yet attracted the attention of the bee keepers. I base 
this conclusion upon the fact that during my study of bee disease- 
there has not yet been received from the bee keepers any sample that 
could be considered a fungous disease. If future investigations 
demonstrate that there exists a fungous disease like the one Howard 
has described, then the name " pickled brood " can be used to desig- 
nate it. When using the term "pickled brood" in the future the 
possible disease, condition described by Howard will be meant. 

A DISEASE OF THE BROOD WHICH IS NOT FOIL BROOD. 

There is a disease of the brood of bees that has attracted consid- 
erable attention among bee keepers that is neither American foul 
brood, European foul brood, pickled brood, chilled brood, nor 
starved brood. This disorder of the brood has for many years been 
recognized by bee keepers as being different from foul brood. Doo- 
little, of America, in 1881 wrote of a disease which he says is similar 
to and called foul brood but which is not foul brood. He writes that 
the larvae die here and there throughout the brood comb and that 
the disease may disappear entirely or it may reappear the next sea- 
son. Jones, of Canada, in 1883 wrote also of a disease which results 
in a dying of the brood, with appearances similar to foul brood; but 
he states that the disease is not foul brood. He says that the bees 
frequently remove the dead brood and that no further trouble ensues, 
Simmins, of England, in 1887 wrote of dead brood which he says is 
not foul brood, and describes the difference in appearance between 
the brood dead of the disease and brood dead of foul brood. He 
states, furthermore, that the condition is different from chilled brood 
and that Cheshire did not find any microscopic evidence of disease 
in larvae dead of the disease. An editorial in one of the bee. journals 
in 1892 is of particular interest at this point. The editor wrote that 
he had recently encountered dead brood which did not seem to be 
infectious and which lacked two decisive symptoms of the real foul 
brood, viz. the ropiness and the glue-pot odor. 

My own study of this dead brood, recognized by the bee keepers 
as being different from foul brood, was begun in 1902. Eight sam- 
ples labeled " pickled brood " were received from the bee inspectors 
of New York State during 1002 and 1003. These samples were ex- 
amined and were found to be practically free from microorganisms. 
The results of these examinations were published in January. 1004. 
Burri. of Switzerland, in 1000 reported the results of the examination 
of 25 samples of brood material thought by the bee keepers to be 



BROOD, \ DISEA8E OF B] I 3. 

diseased. He placed the results of his examinations under the follow- 
ing headings: "Sour brood," "stinking foul brood," "nonstinking 
foul brood," and "* < l»-:i « 1 brood free from bacteria." Pour <>f ili«' 25 
sample- examined contained dead brood free from bacteria and unac- 
companied by other diseases. Kiirsteiner, of Switzerland, in L910, 
in classifying the results obtained from -:i 1 1 1 j »K •- examined by him, 
made the -nine classification as made by Burri. During the past six 
826 samples of this disease have been received by the Bureau 
of Entomology and diagnosed in it- bacteriological laboratory. 

There is, therefore, n disorder attacking the brood <>f bees in which 
brood dies, but in which there has n<>t been demonstrated anj micro- 
organism to which tlic cause of the trouble could be attributed. For 
this disease the name of "sacbrood " is here suggested. 

rm \ \ mi BAI BBOOD. 

A- stated, my first examination of this dead brood was made in 
1902, when samples were received < 1 i :• !_rii<>-«-. I by bee keepers as 
"pickled brood." The fad was easily determined at thai time that 
tin- disease could not lie considered n fungous disease and was there- 
fore not pickled brood. In the past m\ preference has been to refer 
to this condition only as the " -o-called pickled hrood." Since the 
<1 i~.:i- t - is not pickled hrood. it will produce less confusion and he 
more scientific if the term "pickled brood " he entirely omitted in 
the mime for the disease. Many larvae dead of this disease can he 
removed from the cell without rupturing their body w;ill. When 

thus removed they have the appearance of a -mall closed sac. This 
character suggested the name "sacbrood." The name has the virtue. 
therefore, of being both appropriate ami brief. 

l Hi: -1 MPTOM8 "i - v BBOOD. 

The strength of a colony in which sacbrood is present is frequently 
not noticeably diminished. When the brood i- badly infected, how- 
ever, the colony naturally becomes appreciably weakened thereby. 
The hrood die- after the t imc of capping. The dead larva' are there- 
fore almost always found extended lengthwise in the cell ami lying 
with the dorsal side against the lower wall. It is not unusual to find 
many larva- dead of this disease in uncapped cell-. Such brood, 
however, had been uncapped by the hee- after it died. In tin- disease 

the cappings are frequently punctured by the hee-. Occasionally a 
capping has a hole through it. indicating that the capping itself had 
never been completed. A larva dead of this disease loses it- normal 
color and assumes at first a slightly yellowish tint. " Brown" i- the 
most characteristic appearance assumed by the larva during it- decay. 
Various shade- are observed. The term "gray" might sometimes 
appropriately be \i~vA to designate it. The form of the larva <\t'.]'] 



4 SACBROOD, A DISEASE OF BEES. 

of this disease changes much less than it does in foul brood. The 
body wall is not easily broken, as a rule. On this account often the 
entire larva can be removed from the cell intact. The content of this 
saolike larva is more or less watery. The head end is usually turned 
markedly upward. The dried larva or scale is easily removed from 
the lower side Avail. There is practically no odor to the brood 
combs. 

THE INFECTIOUS NATURE AND CAUSE OF SACBROOD. 

In the study of samples of this disease received directly from bee 
keepers no microorganisms have been found, either culturally or 
microscopically, to which the cause of the disease can be attributed. 
This fact, together with the fact that the disease often disappears 
without any great loss to the colony, would tend to indicate that the 
disease is not infectious. The experimental evidence which I have 
obtained proves, however, that the disease is infectious. 

EXPERIMENTAL WORK WITH SACBROOD. 

Evidence has been obtained by me that sacbrood can be trans- 
mitted from diseased to healthy brood. Three healthy colonies were 
inoculated each with diseased material from a different locality, and 
in each of these three experimental colonies the disease was pro- 
duced. These results indicated at once that sacbrood is an infec- 
tious disease. The microscopical and cultural study of the infected 
and dead brood in these experimental colonies, as in the case of the 
diseased brood in samples direct from the apiary, failed to show 
any organism to which the cause of the disease could be attributed. 

This led naturally to a study of the condition to determine whether 
or not the virus of the disease was so small that it had not been seen. 
To obtain evidence on this point material containing the virus was 
filtered, using an earthenware filter. The three colonies in which 
the disease had been produced experimentally furnished the disease 
material for the experiments. Larvae, sick and dead, of sacbrood 
were picked from the combs, crushed, and diluted with sterile water. 
This suspension was filtered by the use of the Berkefeld filter. From 
each of the three diseased colonies a separate filtrate was obtained, 
which was fed in sirup to healthy colonies. Six colonies were thus 
fed — two with each of the three separate filtrates. As a result of 
these inoculations sacbrood with typical symptoms of the disease was 
produced in all of the six colonies thus fed. 

One more experiment will be mentioned at this time. In this the 
diseased brood used was taken from one of the colonies in which 
the disease had been produced by feeding filtrate. Disease material 
from this colony was filtered as before and fed to two healthy colonies, 



BROOD, \ DISE \>i OF BEES. 

with the result thai sacbr i was produced in each. It might be 

mentioned here also that other experiments made indicate that the 
virus i-> killed by the application of a comparatively small amount 
of heat ■ 

l ii colonies, therefore, Bacbrood has been produced experiment 
ally by feeding t<> healthy colonies the virus of this di <;i~c. In B 
of the 11 colonies the disease was produced by virus that had passed 
through the Berkefeld filter. The disease, therefore, which bee 
keepers have for a long time recognized as being different from either 
American or European foul brood Im^ now been demonstrated to be 
:in infectious disease that is caused by a filterable \ini-. 

The conclusion to lx v drawn from thi> work, therefore, is that 
Bacbrood is an infectious disease of the brood <>f bees caused bj an 
infecting agent thnt is so small, or of such m nature, ihnt it will 
l>;i-^ through the pores of a Berkefeld filter. 

The three principal brood diseases, thru, are now :ill known to 
be infectious. These diseases are: American foul brood, caused by 
Hit, illns larvce; European foul .brood, caused by BaciUtu pluton; 
niitl sacbrood, caused by a filterable virus. 

Approved : 

James Wn a »n, 

S n inn/ of ■ Igrit ultun . 

Washington, I). ('.. December /" 1912. 



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